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Heavy charged gauge boson, W’, search at Hadron Colliders

Heavy charged gauge boson, W’, search at Hadron Colliders. YuChul Yang ( Kyungpook National University) (PPP9, NCU, Taiwan, June 04, 2011). This talk is based on the result of Search for W’ decaying to electron and MET in 5.3 fb -1 @CDF and 36 pb -1 @CMS. e. n.

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Heavy charged gauge boson, W’, search at Hadron Colliders

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  1. Heavy charged gauge boson, W’, search at Hadron Colliders YuChul Yang (Kyungpook National University) (PPP9, NCU, Taiwan, June 04, 2011) • This talk is based on the result of Search for W’ decaying to electron and MET in 5.3 fb-1 @CDF and 36 pb-1@CMS. June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  2. e n Motivation (W’ gauge boson) SU(2)RX SU(2)LX U(1)B-L • Left-Right Symmetric Model • Of weak interaction by spontaneous symmetry breaking in the right-handed sector, W’ boson obtains its mass W’/Z’ SU(2)LX U(1)Y W/Z • Signal Model • Right-handed neutrino is light and stable. • Coupling of W’ to fermions is the same as for W • No mixing between W’ and the other gauge bosons. • Decay channels W’ to WZ is suppressed • Decay width of W’ scales with its mass. U(1)EM • Production and Decay • W’ can be production in both ppbar and pp collisions through qqbar annihilation • Decaying to A lepton-neutrino • Decaying to A quark pair (include tb channel) June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  3. CDF W’ Search (W’ → electron + MET) p-pbar Collision at 1.98 TeV with 5.3 fb-1 data June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  4. Data Samples • Looking for the excess events over than SM background in high transverse mass region. • Data : Inclusive High Pt electron sample • 5.3 fb-1 (taken in Feb. 2002 ~ Jun. 2009 ) with good run • Level3 electron trigger path • ELECTRON_CENTRAL_18, ELECTRON70_L2_JET, W_NOTRACK • Background and Signal Samples • PYTHIA MC samples • Multijet Background : from data driven June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  5. Event Selection June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  6. Electron Energy Correction • Using invariant mass of Z to ee sample June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  7. Electron Id. Efficiency • Z →ee Sample used • NTT : both electrons passing Tight Cut. • NTP: one passing Tight, the other passing Loose Cut • Total Efficiency June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  8. Background Estimation • MC background : • W boson : including real electron and MET in final states • Z boson : one electron is mis-measured and then produce as MET • Multijet(QCD) background : data-driven method (next page) June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  9. Multijet Background Estimation Data-driven method adopted June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  10. Multijet Background Estimation June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  11. Background and Data Comparisons Good agreement!! June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  12. The Highest mT Event Display June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  13. W’ Signal : cross-section and width • W’ mass = [500,1300] GeV/c2, ~50k events for each mass points • PYTHIA with CTEQ5L PDFs • W’ →tb • Br(ele.+neu.) : ~ 8.4 % • Cross-section and width June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  14. W’ : generated mass distribution • Before event selection (from PYTHIA generated information) Tails : very heavy input( W’ mass) made large of tail in low mass region June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  15. W’ : PDF Influence (low tails) • PDF heavily suppress high mass production region due to limitation of parton energy carried by quarks in Tevatron energy and this is also reported by D0 [PRL100, 031804] June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  16. W’ : MC Acceptance X Efficiency • Electron and MET > 25 GeV cut : due to the low tails in generation • The efficiency of the other cuts are flat as a function of W’ mass June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  17. W’ signal and background June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  18. Search W’ : Mt fitting • Search for excess in the mT dist. over SM backgrounds • Variable Binned maximum likelihood method • Use Poisson probability with a Gaussian constraining on multijetbg June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  19. Mt Fitting Result • Good agreement between the data and background expectation • No statistically significant excess observed for W’ and we set the mass limit for W’ June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  20. Systematic Uncertainties • Total Uncertainties • PDF : • weighting method • ISR/FSR : • changing PYTHIA parameters • Electron Energy Correction : • 1% asigned • Jet Energy Correction : • MET is re-corrected with JES ±σ • Multijet background : • calculated with variable electron and qcd samples • Cross section : • weighting method June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  21. CDF W’ → electron+MET : Limits • Bayesian 95% CL limit calculated • both the shape and rate systematic uncertainties are incorporated • 1000 times pseudo experiment is performed for Expected Limits. • Used random generated events from the background expectation. June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  22. CMS W’ Search p-p Collision at 7 TeV with 36 pb-1 data June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  23. Event Selection • Preselection • Good primary vertex • At least 1 electron with ET > 25 GeV and H/E < 0.1 • Used MET from particle flow algorithm • Single electron trigger path • 1 good high pT electron (HEEP) • Requirement : June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  24. Background Estimation • Need to determine both the shape and normalization of the transverse mass. • W → ele + neu. : Shape from MC, yield from data-driven (fit of ET/MET method) • QCD multijet : Data-Driven Method • The other backgrounds from MC June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  25. W and QCD Background (Fit of ET/MET) • In two body decay, the energy of the neutrino and electron are expected to be mostly balanced in the transverse plane, and then the ratio of ET is around 1 MT distributions normalized to the region 0.4 < ET/MET < 1.5 June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  26. Background and Data Comparisons June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  27. Transverse Mass distributions Good agreement in both background prediction and observed data in the MT distribution(left) and the cumulative distribution(right) June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  28. The highest MT Event Display June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  29. Systematic Uncertainties June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  30. Number of Event * Other background : gamma+Jet , W→μν, Drell-Yan,WW,WZ,ZZ, single top * Table includes both statistical and systematic uncertainties added in quadrature (does not include lumi uncertainty) June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  31. CMS W’ → ele+MET : Limits • Bayesian 95% CL limit calculator. • Cut-and-Count Method, cut point (> 0.5 TeV)from the best expected limit. June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  32. Summary/Current W’ Limits • mW’ > 1.12 TeV/c2 (5.3 fb-1@CDF; W’ → electron + neutrino) [PRDRevD.83.031102] • mW’ > 1.49 TeV/c2 (36 pb-1@ATLAS; W’ → electron/muon + neutrino) [arXiv:1103.1391] • mW’ > 1.58 TeV/c2 (36 pb-1@CMS; W’ → electron/muon + neutrino) [arXiv:1103.0030] June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  33. Thank you June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  34. backup June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  35. Summary • For search results on heavy gauge boson, W’ decaying to an electron-neutrino pair, found no statistically significant excess observed in 5.3 fb-1 of data • Set the W’ boson mass limit with mW’ > 1.12 TeV/c2 @95% CL ,assuming manifest left-right symmetric model • Publication June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  36. Tevatron • Proton-antiProton colliding with center of mass 1.96 TeV This analysis June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

  37.  = -1  = -2 CDF Detector • Tracking System • Silicon Detector • Central Outer Tracker • 1.4 T B-field • Calorimeter • ElectroMagnetic • Hadron • Muon Detection • Trigger System • Level3 (25000/300/100 Hz) • High pT Lepton • Missing ET • Jets June04, 2011, PPP9, NCU, Taiwan, Yuchul Yang

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